feat(#29): implement cron job configuration

- Add CronSchedule model to Prisma schema
- Implement CronService with CRUD operations
- Add REST API endpoints for cron management
- Create MoltBot plugin skill definition (SKILL.md)
- TDD: 9 passing tests for CronService

apps/api/src/cron/cron.controller.ts

@@ -0,0 +1,88 @@
+import {
+  Controller,
+  Get,
+  Post,
+  Patch,
+  Delete,
+  Body,
+  Param,
+  UseGuards,
+} from "@nestjs/common";
+import { CronService } from "./cron.service";
+import { CreateCronDto, UpdateCronDto } from "./dto";
+import { AuthGuard } from "../auth/guards/auth.guard";
+import { WorkspaceGuard } from "../common/guards";
+import { Workspace, RequirePermission } from "../common/decorators";
+import { Permission } from "@prisma/client";
+
+/**
+ * Controller for cron job scheduling endpoints
+ * All endpoints require authentication and workspace context
+ */
+@Controller("cron")
+@UseGuards(AuthGuard, WorkspaceGuard)
+export class CronController {
+  constructor(private readonly cronService: CronService) {}
+
+  /**
+   * POST /api/cron
+   * Create a new cron schedule
+   * Requires: MEMBER role or higher
+   */
+  @Post()
+  @RequirePermission(Permission.WORKSPACE_MEMBER)
+  async create(
+    @Body() createCronDto: CreateCronDto,
+    @Workspace() workspaceId: string
+  ) {
+    return this.cronService.create({ ...createCronDto, workspaceId });
+  }
+
+  /**
+   * GET /api/cron
+   * Get all cron schedules for workspace
+   * Requires: Any workspace member
+   */
+  @Get()
+  @RequirePermission(Permission.WORKSPACE_ANY)
+  async findAll(@Workspace() workspaceId: string) {
+    return this.cronService.findAll(workspaceId);
+  }
+
+  /**
+   * GET /api/cron/:id
+   * Get a single cron schedule
+   * Requires: Any workspace member
+   */
+  @Get(":id")
+  @RequirePermission(Permission.WORKSPACE_ANY)
+  async findOne(@Param("id") id: string, @Workspace() workspaceId: string) {
+    return this.cronService.findOne(id, workspaceId);
+  }
+
+  /**
+   * PATCH /api/cron/:id
+   * Update a cron schedule
+   * Requires: MEMBER role or higher
+   */
+  @Patch(":id")
+  @RequirePermission(Permission.WORKSPACE_MEMBER)
+  async update(
+    @Param("id") id: string,
+    @Body() updateCronDto: UpdateCronDto,
+    @Workspace() workspaceId: string
+  ) {
+    return this.cronService.update(id, workspaceId, updateCronDto);
+  }
+
+  /**
+   * DELETE /api/cron/:id
+   * Delete a cron schedule
+   * Requires: ADMIN role or higher
+   */
+  @Delete(":id")
+  @RequirePermission(Permission.WORKSPACE_ADMIN)
+  async remove(@Param("id") id: string, @Workspace() workspaceId: string) {
+    return this.cronService.remove(id, workspaceId);
+  }
+}